Bit holder for trapezoidal type cutter bits and manufacture thereof



March 18, 1958 ET AL 3 me n 2 w," m 7 :5 a 2 m w 8 V T mmz A 2 Ba a. 5 0 M T C. B. KREKELER BIT HOLDER FOR TRAPEZOIDAL TYPE CUTTER BITS AND MANUFACTURE THEREOF Filed 001.. 6, 1955 BIT HOLDER FOR TRAPEZOIDAL TYPE CUTTER BITS AND MANUFACTURE THEREOF Claude B. Krekeler and Armin 0. Brnestle, Qincinnati, Ohio, assignors to The Cincinnati Mine Machinery Co., Cincinnati, Ohio, a corporation of Ohio Application October 6, 1955, Serial No. 538,942

11 Claims. (Cl. 262--33) The invention relates to the provision of bit holders, particularly for the so-called trapezoidal type of mining machine cutter bits of throw-away character. The bit holders are usually employed in sockets formed in links of a mining machine cutter chain, although they may be employed in connection with moving elements of other types of mining machinery.

It is an object of the invention to provide a cutter bit holder having a number of particular advantages, among which may be mentioned the provision of an adequate flat stop or abutment for engaging a face of the cutter bit and sustaining the main cutting thrusts, together with elements surrounding other portions of the cutter bit and coacting with the abutment to give a wedging action such that the bit will be adequately held by the holder in cutting position so long as the withdrawal of the bit in the direction of its major axis is prevented. The provision of adequate clearance for an unused bit point'is also a feature of the invention.

Another object of the invention is the provision of a bit holder structure having the above advantages which can be made more cheaply, and in operations requiring fewer steps.

These and other objects of the invention, which will be set forth hereinafter or will be clear to one skilled in the art upon reading these specifications, are accomplished by that structure and arrangement of parts and in that procedure of which certain exemplary embodiments will now be described. Reference is made to the accompanying drawings wherein:

Fig. 1 is a partial elevational view of a cutter chain including a socket link and set screw, a bit stop, a bit holder, and a cutting bit.

Fig. 2 is a side elevation of one form of the bit holder of this invention with a bit in place therein.

Fig. 3 is a perspective view of a trapezoidal bit.

Fig. 4 is a front elevation of the bit holder of Fig. 2 with the bit removed.

Fig. 5 is a view of the holder similar to that of Fig. 2 but with parts broken away along the section line 5-5 of Fig. 4 to show interior construction.

Fig. 6 is a similar view of a bit holder in an initial stage of manufacture.

Fig. 7 is a similar view showing a later stage of manufacture.

Fig. 8 is a similar view of another form of bit holder in an initial stage of manufacture.

Fig. 9 shows the same bit holder in a later stage of manufacture.

Fig. 10 is a perspective View of an anvil member.

A trapezoidal bit of known form is illustrated at 1 in Fig. 3. The bit holder is formed, as is usual in the art, by cutting suitable steel rod stock of generally diamond shape cross-section along slantwise, transverse, nonparallel planes. After manufacture the bit is tempered to give it cutting qualities; and it may be tipped with hard alloy if desired. It will be seen to have oppositely directed cutting points 2 and 3 which are designed for alternative States Patent 2,827,275 Patented Mar. 18, 1958 ice use. After both cutting points are worn to the extent that eflicient cutting can no longer be done, the bit is discarded. The term trapezoidal refers to the shape of the bit in side elevation, but should not be regarded as a term of express limitation. Bits which are triangular in side elevation may be employed; and variations in the shapes of the cutting points may be made. The term, however, is indicative of a recognized class of cutting bits to which this invention primarily pertains.

As illustrated in Figs. 2, 4 and 5, the exemplary bit holder of this invention is a unitary metallic body having a shank 4 and a head 6. The head is hollow, providing a central space into which an end of the trapezoidal bit may be passed. In the exemplary structure, the hollow is generally of triangular cross-section. It is, however, characterized by a basal flat or upstanding abutment 7 which serves to engage a face 8 of the cutting bit. The head 6 is also characterized by integral portions 9 and 10 which surround other portions of the bit to hold it in place and provide a wedging action in cooperation with the abutment 7. It will be evident that one of the cutting points of the bit extends into and in some instances through the bit holder. It is necessary to provide clearance for this cutting point.

The bit holder of the invention is most conveniently necessary limitation of the invention. It is sufiicient topoint out that, as illustrated in Fig. 6, the blank is externally shaped to the required configuration by drop. forging and is also provided with an interior hollow in the head (indicated at 11 in Fig. 6) which hollow extends. generally transversely of the shank, is shaped to its final form, and is complete with the abutment means 7. The. hollow, as illustrated in Fig. 6, however, does not supply the clearance for the lower cutting point of the bit.

This clearance, in accordance with the invention, is supplied by a simple operation of drilling into the op posite end of the head 6 a hole, somewhat larger thanthe inner end of the orifice 11, to a depth such that the drilled hole 12 meets and joins with the orifice 11, as illustrated in Fig. 7. This may be accomplished by means of a drill 13 suitably power actuated, the holder being held in a suitable jig during the drilling operation.

The manner in which the bit 1 seats in the bit holder will be abundantly clear from Figs. 2 and 5. In Fig. 1 there is shown a portion of a mining machine cutting chain of known form, having a socket link 14, a portion of which is laterally prolonged, as at 15, to provide a socket element. The socket element is perforated as at 16 to accept the shank 4 of the bit holder which is held in place by a set screw 17. Forward and rear portions 18 and 19 of the prolongation preferably extend upwardly to provide abutments. An anvil member 20 is provided at the front of the rear abutment 19; and the rear end of the bit holder engages this anvil member so that the rearward thrusts of cutting are transmitted to the abutment. The anvil member may be made integral with the member 19; but it is preferred to form the anvil member as a replaceable unit. When so made, the anvil member is preferably provided with a rearward extension 21 engaging in a hole in the abutment member. If desired for alignment purposes, the rear end portion of the bit holder head 6 may be provided with a tooth 22 which can engage in a slot 23 in the anvil member.

is desired to be claimed andisecured by Letters Pa The forward abutment 18 of" the socket member is also provided with an anvil element 24. This is "shown-in 'Fig. asa replaceable member having a forward lug or projection adapted to fit into a perforation in the forward log 18. 'The' forward anvil memberhas arecess in its rearward face-to V accept 'a rdrwara rse of the cutter bit: The slantwi'se wall of this recess exerts a wedging action on the bit,"as=will be evident, tending tourge the bit into the bit holder. r 7 "By these simple means, the bit holder of this invention is enabled to hold bits firmly during the cutting operation as we'll as to be slightly adjustable so ais'to acc on rnodate bits, the dimensions of 'which are not always precisely by e ti edp r;

holder structure, as illustrated at Fig. 8, by-"meansaraplunger 27 which formsthe recess ll, ashereinabove described; The blank is then transferred to a W characterized by an orifice beneath the'recess," and asecif oridforg ingoperation is accomplished by ineans of' a plunger 28 having a nose '29 which "will ac cohiplish' ance space for the unuse'd'bit' point; as will be evident.

Under circumstances, it is possible tqf ac'5onip1ish} a piercing of the head behind the reces's 11,-as illustrated V at 30 in Fig. 9. The piercing of the-headprovides clearthe entire forging operation in a'single'die' with a'siirgle' plunger; The use of two plungers be: indicated where the direction of motion of the twopl ung'ersf is required to be recess 11. I

"difie'rent with respectito the the Modifications may be made in the inventionwithout departing frorn'the' spirit ofit. -rhe-inv'es1;ien;haeing-i been described in certain ex e plary' embodimentsjwhat 1. A'bit holder for-a removable cuttingbit havingoppositely' directed cutt ng points, the bi t-being substantially) trapezoidaltinl side elevation, generally diamond shaped in central crosssection ahdi 'charact'eriaed"byfangulailyf; con

relatedfface planes at the sidesfoif tlzie 'trapegoi V formation, said bit holder comprising an finte gral metal strnctiire having a" head andiafshankif'said"head having a tapering reessP-of generallf triangular ft r ansvei'jsecross sectionalshape tanned; therein I side aiidadapted toieceive a minor p'ortion of thef bod y' ofjsaidl pa n aq q n h ;a ..f th S i s l ass c 2 1.

' the cuttil'l bit lies along the base of the said triangular recess and another portion of the head within'said recess contacts' a portion of the said bit to hold the said bit downwardly with its said face plane in contact with the lower portion of the interior of said recess, whereby said bit is held against tilting so long as it is fully thrust into the said recess, there being a perforation of different cross sectional shape extending from the'inner end of said recess s eimebirdie te; or d head 1 Pr clearance for a cutting point of the said bit.

2. "l'li'estr'ucture claimed in claim 1' wherein saidlast mentioned perforation is adrilled hole larger in diameter 7 than the inner end of "said recess.

3. The structure; claimed in claim 1 in which the base of said recess is formed with an upstanding flat abutment member to engage-said one of said face planes of the cutter bit and sustain the inward thrusts of cutting.

4. The structure clairned in claim 1 formed by drops forging.

'5.}-The structure claimed 2 formed by drop forging.

6,-A-"process of making cutter bit holders for trape:

zoidal bits"wl iich conipris'e's' drop forging a metal blank" to provide ahead anda'shank, with'-a"taperingrecess formed therein from one side, said'rec'ess having a gen tionof different cross-'se'c'ti'on'i meeting"said recess from theop'posit side of sai'd "head to provide clearance'for oin'tOf a cutteflbitia portion ofwhichis' ontained in said-recess.

7. "The process claimed in claim 6*wherein said perfora- '9;- Theprocess cl' is provided-at its base-with an upstanding flat abiltniei'i't for engaging a face ofacutting bit-tosnsta f the i ilOJThe procfe's's'claimed in claim wherein saidp'er foration is'formedby' drilling. I a a 11. Theprocess claimed in claim 9 whereinsaid perforation is formedby piercing; i I i References Cited in the file of this patent UNITEQT TATIESQ A ENTS.

1,373,725, Heiby, et al., Apr. 5, .1921 2,021,703 Sparks Nov; 19, 1935 2,262,592; Stephens Nov. 11; 1941 2,389,517 'Labadie Nov; 2Q,--19451 f j e 'sd f d in 6 wherein said: perfora Morrow Feb. 4,: 19.47 

